[llvm] [LV] Pre-commit test for #128062 (PR #164801)

[Florian Hahn via llvm-commits]

fhahn wrote:

> > Did you check this works as expected? I think to trigger narrowInterleaveGroups, a target-specific test is needed, as it checks the size of the vector against the target vector size.
> 
> I got a diff with #164839, although that PR needs more thought?

Got it, thanks! It looks like https://github.com/llvm/llvm-project/pull/164839 contains additional tests, could you include them here as well?

https://github.com/llvm/llvm-project/pull/164801